On the road to ITER NBIs: SPIDER improvement after first operation and MITICA construction progress

To reach fusion conditions and control the plasma configuration in ITER, the next step in tokamak fusionresearch, two neutral beam injectors (NBIs) will supply 16.5 MW each, by neutralizing accelerated negativehydrogen or deuterium ions. The requirements of ITER NBIs (40A/1 MeV D- ions for <=1 h, 46A/870 keV H- ionsfor <=1000 s) have never been simultaneously attained. So in the Neutral Beam Test Facility (NBTF, ConsorzioRFX, Italy) the operation of the full-scale ITER NBI prototype (MITICA) will be tested and optimised up to fullperformances, focussing on accelerator (including voltage holding), beam optics, neutralisation, residual ionremoval. The NBTF includes also the full-scale prototype of the ITER NBI source with 100 keV particle energy(SPIDER), for early investigation of: negative ion production and extraction, source uniformity, negative ioncurrent density and beam optics.This paper will describe the main results of the first two years of SPIDER operation, devoted to characterizingplasma and beam parameters, including investigation of RF-plasma coupling efficiency and magnetic filter fieldeffectiveness in reducing co-extracted electrons. SPIDER is progressing towards the first caesium injection, whichaims at increasing the negative ion density. A major shutdown, planned for 2021, to solve the issues identifiedduring the operation and to carry out programmed modifications, will be outlined.The installation of each MITICA power supply and auxiliary system is completed; in-vessel mechanicalcomponents are under procurement by Fusion for Energy (F4E). Integration, commissioning and test of the powersupplies, procured by F4E and QST, as the Japanese Domestic Agency (JADA), will be presented. In particular,1.0MV insulating tests were carried out step-by-step and successfully completed. In 2020 integrated tests of thepower supplies on the accelerator dummy load started, including the assessment of their resilience to acceleratorgrid breakdowns using a short-circuit device located in vacuum.The aggressive programme, to validate the NBI design at NBTF and to meet ITER schedule (requiring NBIs inoperation in 2032), will be outlined. Unfortunately, in 2020 the coronavirus disease infection affected the NBTFactivities. A solution to proceed with integrated power tests despite the coronavirus is presented.